Examples for the case of no errors:

> java Summing 0
0
> java Summing 0 3 5.6
2
> java Summing 1
0.0
> java Summing 1 2
2.0
> java Summing 1 2 3
5.0
> java Summing -1
0.0
> java Summing -1 2
0.5
> java Summing -1 2 3
0.8333333333333333
> java Summing 2
0.0
> java Summing 2 3
3.0
> java Summing 2 3 2
6.0
> java Summing 2 3 2 4
10.0
> java Summing 2 3 2 4 5
26.0
> java Summing -2
0.0
> java Summing -2 2
0.5
> java Summing -2 2 3
0.16666666666666666
> java Summing -2 2 3 2
0.6666666666666666
> java Summing -2 2 3 2 3
0.3333333333333333

Examples for error cases:
> java Summing
> echo $?
1
> java Summing -1 4 3 0 2
> echo $?
2
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